Erysimum
Family: Brassicaceae
Common Name: Perennial Wallflower
These hardy, annual, biennial and perennial plants are found in the wild only in the northern hemisphere. They look pretty in rockeries and borders, and are also well suited as edging and bank plantings. The leaves are mostly entire and the flowers come in various shades of yellow through to orange, pink and purple.
Species
E. asperum, zone 4, is a biennial or short-lived perennial with orange flowers in spring and early summer.
E. kotschyanum is a perennial with bright yellow flowers, generally used as a groundcover as it grows to only 15 cm (6 in).
E. linifolium, a perennial, to 45 cm (18 in), produces rosy lilac flowers from mid-spring to the early autumn. Cultivars are usually more available than any of the species.
Cultivation
Erysimum will grow in any garden soil, but requires a sunny spot. Clip over perenÂnials lightly after flowering, to maintain a comÂpact shape. Propagate all from seed sown in spring and perennials from softwood cuttings in summer.
Climate
Zone 6 for most species.